Adjustable stock lifter



Feb. 13, 1968 E. MARSZAL ADJUSTABLE STOCK LIFTER 2 Sheets-Sheet 1 FiledSept. 27, 1965 INVENTOR.

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WITNESS nv WWW/u W $11M 1 7 (a Leonard E. Murszol United States Patent"Ce 3,368,383 ADJUSTABLE STOCK LIFTER Leonard E. Marszal, 14200 IronwoodDrive NW., Grand Rapids, Mich. 49504 Filed Sept. 27, 1965, Ser. No.490,611 Claims. (Cl. 72-361) This invention relates to the constructionof a component of the so-called progressive dies used for massproduction of pieces formed and cut from strip sheet metal. This type ofdie is used when a sequence of die operations is required to completethe piece, and when the production run is large enough to justify thecost of the multiple-stage die unit. The die itself is essentially aseries of dies in accurately-spaced sequence, and the strip of sheetmetal is moved through the die in increments so that the piece isindexed from one stage to the other as each operation is performed. Acup-shaped article, for example, might go through a series of operationssuch as the following:

(a) Blanking out portions of the strip to isolate the material to beused to form the finished part, leaving portions attached to the strip.

(b) A succession of drawing operations stretching the material fromplanar to cup-shaped configuration.

(c) Final trim, and severing of the part from the strip.

As the strip is moved through the die, it is necessary to provide aguide to position it when the die is open. The strip must be supportedfar enough above the lower die structure to eliminate interference asthe drawn portions of the strip are moved ahead. The device used forguiding and lifting the stock to this position is known as a stocklifter, and is widely used in die construction. A particular die willfrequently use a pair of these lifters between each station, and it isobvious from this that the number of these devices used in die making istremendous. The present invention is an improvement in these devices,particularly with regard to the lateral positioning of the stock strip.

A troublesome problem in die making has been the tendency of the stockstrip to narrow during the drawing operations as the metal is stretchedand pulled out of the plane of the strip. The position of the stocklifters must be correspondingly altered if the strip is to be guidedaccurately. A skilled die maker will normally try out a particular drawto determine the amount of reduction of stock width, and he will thenlocate his lifters accordingly in the die blocks. The lifters themselvesare usually cylindrical in outer configuration, and are received insuitable holes bored in the proper locations. Estimating the amount ofdeviation from a straight line which will be required in a row of stocklifters to accommodate reduction in stock width is essentially atrial-and-error procedure, and requires the ultimate in skill andexperience on the part of the die maker and die designer. Even then,slight variations in hardness or thickness of material (not to mentionvariation in original Width) will inject variables that are verydifficult to allow for in such a piece of guesswork. Rather than facethe problem of having to re-locate the stock lifters, there will be atendency on the part of the die maker to allow a little more freedom ofmovement of the stock strip than is desirable. The present inventioneliminates the need for this allowance of excess freedom, and alsoeliminates the need for a carefully-controlled trial draw in order todetermine the amount of stock width reduction. With the presentinvention, a skilled die maker will be able to determine from his pastexperience approximately the amount of reduction in strip width, and thelateral adjustability provided by the invention will enable the diemaker to locate the strip accurately and maintain the adjusted position.The amount of work that this will save the die maker and die designer is3,368,383 Patented Feb. 13, 1968 obvious, and it is also obvious that acompleted die can be modified to accept a limited variation in stockwidth by a relatively minor adjustment. This lateral adjustability isprovided without interfering with the projected cylindrical surfacedefining the periphery of the stock lifter, with the result that thelifter is able to reciprocate during the die movement without requiringthe machining of clearance areas beyond that which is required forconventional stock lifters.

The several features of the invention will be analyzed in detail by adiscussion of the particular embodiments illustrated in the accompanyingdrawings. In the drawings:

FIGURE 1 is a section on a horizontal plane taken between the upper andlower die members, as indicated at the plane shown in FIGURE 2.

FIGURE 2 is a sectional elevation on the plane 2-2 of FIGURE 1, on anenlarged scale.

FIGURE 3 is a view on an enlarged scale of the stock lifter shown at thelower right portion of FIGURE 1.

FIGURE 4 is a view on an enlarged scale showing the stock lifter at thelower left portion of FIGURE 1.

FIGURE 5 is a sectional elevation corresponding to FIGURE 2, with thedie in the closed position.

FIGURE 6 is a perspective view showing the upper portion of the body ofthe stock lifter.

FIGURE 7 is a perspective view showing an inverted head of the stocklifter.

FIGURE 8 s a view of the body of a modified form of the invention.

FIGURE 9 is a sectional elevation showing the head construction used inconjunction with the FIGURE 8 modification.

FIGURE 10 is a perspective view of the upper portion of the body of afurther modification of the invention.

FIGURE 11 is a sectional elevation showing the head construction used inconjunction with the FIGURE 10 modification.

FIGURE 12 is an exploded view showing the components of the form ofstock lifter incorporated in FIG- URES 1 through 7.

Referring to FIGURES 1 through 7, and 12, the illustrated dieconstruction includes the shoe 20 provided with a group of guide pins 21engageable with the bearings 22 of the upper member 23 of the die set. Adie block assembly is shown at 24, which is secured to the die shoe by aseries of screws 25. It is conventional practice to use locating dowelsin addition to these screws, but these are not shown on the drawings.The die block assembly 24 will normally be made up from a group ofsegments fastened individually to the shoe 20. Since this portion of theconstruction of the die forms no part of the present invention, thesedetails are omitted here. The construction normally associated with theupper member 23 of the die set will include a group of punches as shownat 26, and also a stripper plate 26a having openings closely surroundingthe punch 26. This plate serves to hold the marginal areas of the strip,and pulls the formed part 27 off the punch as the die moves to the openposition shown in FIGURE 2. The stripper plate 26a will normally beprovided with guide pins in the form of the bolts 28. These bolts havethreaded engagement with the plate, and are mounted for reciprocatingmovement in the upper member 23 of the die set. Springs 29 surroundingthe bolts 28 will bias the plate 26a to the position shown in FIGURE 2.This type of die construction is conventional.

As the die moves to the open position shown in FIG- URE 2, the strip 30providing the material for the parts 27 is moved in the direction of thearrow appearing in FIGURE 1. As each piece 27 encounters the operatingstations of the die, it is usual practice to first punch a locating holeas shown at 31. This will be used at subsequent stations to position thestrip for the succeeding die operations more accurately than is possiblewith the stock lifters shown at 32. The latter function as guides toposition the strip accurately enough so that the fianl positioning atthe locating holes 31 can be accomplished. During the formation of thepiece 27, the areas 33 are blanked out to isolate a portion of the stripfrom which the parts 27 are to be made. This isolation permits the metalto draw Without substantially effecting the length of the strip. Theparts 27 are then drawn in successive stages to form a complete piece,and are fianlly trimmed and severed from the strip 30. During theshifting of the strip 30 for these successive operations, the stocklifters 32 will participate in a vertically-reciprocating motion inresponse to the movement of the upper section of the die. The openposition of the die is shown on FIGURE 2, and the closed position inFIGURE 5.

During the successive drawing operations, the width of the strip 30 willdecrease from right to left. The width of the strip between the lifters34- and 35 is substantially less than between the lifters 36 and 37. Theamount of deviation from a straight line which the die maker willprovide for the row of stock lifters along the edge of the strip can bedetermined approximately from his past experience, and the adjustabilityprovided by the present invention will make it possible for the diemaker to make final adjustments'to the lifters so that the stock strip30 can be guided accurately as it moves through the die. Thisadjustability is provided by a rotatable mounting of the head 38 withrespect to the body 39 of the lifter. A slot 40 in the side of the headreceives the edge of the stock strip 30, and the base of the slot 40 isformed by a preferably cylindrical surface 40a which is eccentric to theaxis of the mounting of the head 38 on the body 39. It is preferablethat the cylindrical surface defining the periphery of the head 38 bedefined by the same geometrical cylinder as that of the body portion 39,with the result that the head would be receivable in the bore in the dieblocks 24 in the down position of the die shown in FIGURE 5. However,loosening of the screw 41 will permit the head 38 to be rotated withrespect to the body 39, with the result that the eccentric surface 40awill bear against the stock strip 30 at variable positions from the axisof the body portion 19 of the lifter. This rotary adjustment can becontinued until the correct bearing position has been obtained. Theadjustment can then be secured by tightening the screw 41, which willengage the radial serrations 42 on the boss 43 with the correspondingserrations 44 in the inner extremity of the recess 45 of the head 38.This configuration is best shown in FIGURES 6, 7, and 12. The radialserrations are most conveniently formed by a process commonly referredto as coining, which is essentially a localized forging operation.

The rotary position of the body 39 with respect to the remainder of thedie structure is maintained through the engagement of the washer 46 withthe recess 47 in the side of the body 39. The washers 46 are mounted inthe die block assembly 24 in suitable counterbored areas as shown at 48,and are held in position with the screws 49. The engagement of thewashers 46 with the shoulder 50 serves to retain the body 39 inengagement with the die structure. The stock lifter then is free toparticipate in the reciprocating vertical movement induced by the actionof the upper die unit and the springs 51 which are installed in thelower die structure. These compression springs apply continuous biasingaction tending to move the lifters to the position shown in'FIGURE 2.

FIGURE 8 shows a modified form of the invention with regard to thearrangement for locking the rotative position of the head with respectto the body. In this modification, the body 52 is provided with aprojecting 4 boss 53 having a polygonal periphery formed by a series offlats as shown at 54. These flats may be formed either by a millingoperation, or may be broached in a single pass if a clearance groove isprovided at the base of the boss 53. The head 55 used with thismodification of the invention may be provided with a set screw 56 whichis engageable with one of the flats 54 to maintain the adjusted positionof the head on the body. A hold-down screw 57 is also necessary, andthis screw should be loosened prior to adjusting the position of thehead 55. As an alternative to the set screw 56, a forging operation canbe utilized which will produce a polygonal configuration in the headrecess similar to that of the periphery of the boss 53, if desired.

The modification shown in FIGURES 10 and 11 provides another arrangementfor locking the rotative position of the head with respect to the bodyof the lifter. The body 58 is provided with a group of depressions 59 inthe shoulder 60, and the head 61 has a recess machined in the undersurface 62 of a sufficient depth so that the ball 63 may be insertedwith a portion projecting for engagement with the recesses 59. Looseningof the holddown screw 64 will permit the head 61 to be rotated to theselected adjustment. The recess 65 engages the boss 66 to position thehead coaxially with the body 58.

The particular embodiments of the present invention which have beenillustrated and discussed herein are for illustrative purposes only andare not to be considered as a limitation upon the scope of the appendedclaims. In these claims, it is my intent to claim the entire inventiondisclosed herein, except as I am limited by the prior art.

I claim:

1. A stock lifter for a die adapted to operate on strip material, saidlifter comprising:

a body normally slideably received in a die block for reciprocatingmovement in response to relative movement of components of said die; and

a head having a transverse slot, said head being adjustably mounted onsaid body, to a plurality of angular positions with respect theretoabout an axis substantially parallel to the axis of said body, the baseof said slot being defined by a surface having portions thereofeccentric to the axis of the mounting of said head on said body; and

locking means releaseably securing the relative position of said head onsaid body.

2. A lifter as defined in claim 1, wherein said body and head havecylindrical peripheral surfaces coaxial with the axis of rotatablemounting of said head on said body.

3. A lifter as defined in claim 1, wherein the base of said slot isdefined by a cylindrical surface eccentric to the axis of the mountingof said head on said body.

4. A lifter as defined in claim 1, wherein said body and head haveaxially interengaged bearing and journal portions, one of said portionsbeing on said body and the other on said head, and said journal portionhaving end serrations engageable with the axially-opposite areaassociated with said bearing portion to lock the adjustment of said headon said body, said locking means including a screw traversing said headand said journal portion to hold said serrations in engagement.

5. A lifter as defined in claim 1, wherein said head and body haveaxially interengageable means at least at two spaced positions todetermine the lateral and angular position of said head on said body.

References Cited UNITED STATES PATENTS RICHARD J. HERBST, PrimaryExaminer.

1. A STOCK LIFTER FOR A DIE ADAPTED TO OPERATE ON STRIP MATERIAL, SAIDLIFTER COMPRISING: A BODY NORMALLY SLIDEABLY RECEIVED IN A DIE BLOCK FORRECIPROCATING MOVEMENT IN RESPONSE TO RELATIVE MOVEMENT OF COMPONENTS OFSAID DIE; AND A HEAD HAVING A TRANSVERSE SLOT, SAID HEAD BEINGADJUSTABLY MOUNTED ON SAID BODY, TO A PLURALITY OF ANGULAR POSITIONSWITH RESPECT THERETO ABOUT AN AXIS SUBSTANTIALLY PARALLEL TO THE AXIS OFSAID BODY, THE BASE OF SAID SLOT BEING DEFINED BY A SURFACE HAVINGPORTIONS THEREOF ECCENTRIC TO THE AXIS OF THE MOUNTING OF SAID HEAD ONSAID BODY; AND LOCKING MEANS RELEASEABLY SECURING THE RELATIVE POSITIONOF SAID HEAD ON SAID BODY.